The 2005 Lockdown was a professional wrestling pay-per-view (PPV) event produced by the Total Nonstop Action Wrestling (TNA) promotion, which took place on April 24, 2005, at the TNA Impact! Zone in Orlando, Florida. It was the first event under the Lockdown chronology and the fourth event in the 2005 TNA PPV schedule. Eight professional wrestling matches and one pre-show match were featured on the event's card. Every match took place inside a six sided steel structure known as the Six Sides of Steel. As a result, Lockdown was the first-ever all steel cage event held in professional wrestling.

The main event was for a NWA World Heavyweight Championship match at TNA's Hard Justice PPV event between A.J. Styles and Abyss. Styles won the match, thus earning his title shot against then-champion Jeff Jarrett at Hard Justice. TNA held the first-ever Lethal Lockdown match during the event. It pitted Team Nash (Diamond Dallas Page, Sean Waltman, and B.G. James) against Team Jarrett (Jeff Jarrett, Monty Brown, and The Outlaw), which Team Nash won. Kevin Nash was originally supposed to take part in the match but was removed due to sickness and was replaced with James. The TNA X Division Championship defense by Christopher Daniels against Elix Skipper was another highly promoted match for the event. Daniels won the bout and successfully retained the title. Jeff Hardy versus Raven in a Six Sides of Steel Tables match was featured on the card, which Hardy won.

This event marked the introduction of the Lethal Lockdown and Xscape matches, which became annually held matches at future Lockdown events. During the event, Chris Candido received a career-ending injury during his tag team match with Lance Hoyt against Apolo and Sonny Siaki, which later led to Candido's death from pneumonia soon after surgery.

Jason Clevett of the professional wrestling section of the Canadian Online Explorer rated the event a 6 out of 10, two marks lower than the 2006 event's ranking by Chris Sokol.

In October 2017, with the launch of the Global Wrestling Network, the event became available to stream on demand.